Graphite as EDM material in mould and die making

Graphite is becoming increasingly important as an EDM material in mould and die making. It offers clear advantages in both milling and EDM compared to other materials. The low thermal expansion of the material ensures excellent dimensional and contour accuracy

Milling graphite

Graphite is not plastically deformable and thus not machinable in the true sense of the word. In the machining process, individual grains are knocked out of the composite in a controlled manner. This leads to an abrasive attack on the cutting surface of the tool and requires a relatively high wear resistance of the cutting material. This effect occurs during dry machining and can be reduced with high cutting speeds. Especially the wear of diamond-coated or PCD tools decreases with increased cutting speed and at a higher feed per tooth, which leads to optimal machining results. At the same time, the increased machining speed further optimises the work result.

Advantages

Reduced costs due to low wear
Increased productivity due to high removal rates
Filigree geometries possible
No rework necessary

EDM with graphite

Graphite electrodes allow significant time and cost savings. Already during the design phase, different mould elements can be combined into one electrode in order to fully exploit the possibilities of modern and powerful EDM machines. The density is lower than that of copper by a factor of 4. This means that even large electrodes can be handled without any problems and with extreme precision.

Advantages

Reduced costs due to long service life
Precise EDM results
Increased productivity
Use of large electrodes possible

Meusburger graphite grades

We recommend using the appropriate graphite grade for the intended application:

Q70

For surfaces from VDI 27 (2.2 μmRa) to VDI 24 (1.6 μmRa) depending on machine technology
Low electrode wear
Good surface
Fast eroding process

Q60

For surfaces of VDI 22 (1.26 μmRa)
Ideal for high-quality finishing work
For highly detailed shapes
Good surface finish with good material removal rate

Q40

For surfaces of VDI 20 (1.0 μmRa)
Complicated electrodes with fine contours
Low electrode wear with good removal rate
For very demanding surface finishes

	Q70	Q60	Q40
Average grain size:	7 µm	6 µm	4 µm
Attainable surface finish	VDI 27 (2.2 µmRa) – VDI 24 (1.6 µmRa)	VDI 22 (1.26 µmRa)	VDI 20 (1.0 µmRa)
Density	1.83 g/cm³	1.86 g/cm³	1.82 g/cm³
Electrical resistance	12.5 µΩ/m	12 µΩ/m	16.5 µΩ/m
Bending strength	54 N/mm²	65 N/mm²	66 N/mm²
Hardness	62 Shore	60 Shore	72 Shore